Up until now, every CGI we have used has required the user to hit a 'submit' button on an HTML page, at which point the entire window is replaced by a new page. You could easily write a program using the skills you have already learned to open a count file, add 1, and replace. It would look something like this:
#******** BEGIN BODY ********
open (GETCOUNT,"<count.log");
#open count log for input
$counter=<GETCOUNT>;
#assign contents of file to $counter
close (GETCOUNT);
#close access to file
$counter++;
#increase $counter by 1.
print "$counter hits";
#print number of hits to users screen
open (PUTCOUNT,">count.log");
#open count log for output
print PUTCOUNT ($counter);
#replace old counter value with new one
close PUTCOUNT;
# close access to file
#******** END BODY *********
If we were to call such a program with a SUBMIT button, the current page would dissapear and be replaced by the output of this program. In order to display the hits on our page, we need a way to execute a program when a page loads, and embed the results back in that same page. This method is called a Server Side Include (SSI).
NOTE: Not all web servers support SSI. Some only work if the pagename ends with ".shtml" or ".html-ssi" and some have it completely disabled for security purposes. If you have difficulty with this exercise, check with your system administrator.
Here's how it works:
 | HTML Form | Guestbook Form | Hit Counters |
